// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_TEST_TEST_PENDING_TASK_H_
#define BASE_TEST_TEST_PENDING_TASK_H_

#include <string>

#include "base/callback.h"
#include "base/location.h"
#include "base/time/time.h"
#include "base/trace_event/trace_event_argument.h"

namespace base {

// TestPendingTask is a helper class for test TaskRunner
// implementations.  See test_simple_task_runner.h for example usage.

struct TestPendingTask {
    enum TestNestability { NESTABLE,
        NON_NESTABLE };

    TestPendingTask();
    TestPendingTask(const TestPendingTask& other);
    TestPendingTask(const tracked_objects::Location& location,
        const Closure& task,
        TimeTicks post_time,
        TimeDelta delay,
        TestNestability nestability);
    ~TestPendingTask();

    // Returns post_time + delay.
    TimeTicks GetTimeToRun() const;

    // Returns true if this task is nestable and |other| isn't, or if
    // this task's time to run is strictly earlier than |other|'s time
    // to run.
    //
    // Note that two tasks may both have the same nestability and delay.
    // In that case, the caller must use some other criterion (probably
    // the position in some queue) to break the tie.  Conveniently, the
    // following STL functions already do so:
    //
    //   - std::min_element
    //   - std::stable_sort
    //
    // but the following STL functions don't:
    //
    //   - std::max_element
    //   - std::sort.
    bool ShouldRunBefore(const TestPendingTask& other) const;

    tracked_objects::Location location;
    Closure task;
    TimeTicks post_time;
    TimeDelta delay;
    TestNestability nestability;

    // Functions for using test pending task with tracing, useful in unit
    // testing.
    void AsValueInto(base::trace_event::TracedValue* state) const;
    std::unique_ptr<base::trace_event::ConvertableToTraceFormat> AsValue() const;
    std::string ToString() const;
};

// gtest helpers which allow pretty printing of the tasks, very useful in unit
// testing.
std::ostream& operator<<(std::ostream& os, const TestPendingTask& task);
void PrintTo(const TestPendingTask& task, std::ostream* os);

} // namespace base

#endif // BASE_TEST_TEST_PENDING_TASK_H_
